feat: mask_url/mask_proxy display maskers; fix: deep_set now indexes into lists on numeric segments (commons-2)

mask_url/mask_proxy redact credentials from connection strings for logging
(display only, not a security control). deep_set previously destroyed a list
when a numeric path segment landed on it (isinstance(nxt, dict) check
replaced the list wholesale); it now mirrors deep_get's list indexing so a
get/set round-trip on the same dotted path never corrupts data, raising
IndexError on an out-of-range segment instead of silently mis-storing.

Signed-off-by: disqualifier <dev@disqualifier.me>

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "commons"
-version = "0.2.3"
+version = "0.3.1"
 description = "small stdlib-based sync helpers: time/timezone deltas, dotted-path dict access, display masking, ip/address tooling, and retry/backoff"
 requires-python = ">=3.10"
 dependencies = []